JP2019149260A - Control method of fuel-cell vehicle - Google Patents

Abstract

To provide a control method of a fuel-cell vehicle, capable of appropriately discharging retained water in both of an end part cell and a central cell in a fuel cell during an idle operation.SOLUTION: A control method of a fuel cell vehicle includes steps of shifting to an intermittent operation mode (YES in step S20) when a shift position enters a P range and becomes an idle operation during a normal operation mode (step S10), starting a fine power generation (YES in step S30), and increasing an auxiliary machine power consumption than a normal situation by continuously operating a cooling water pump 52, or increasing the rotational number of the cooling water pump 52 (step S40).SELECTED DRAWING: Figure 5

Description

  The present invention relates to a control method for a fuel cell vehicle.

2. Description of the Related Art There is known a fuel cell system that generates power using an electrochemical reaction between a fuel gas containing hydrogen and an oxidizing gas containing oxygen.
For example, Patent Document 1 discloses that in a fuel cell system, a heater is provided at the end of the fuel cell to suppress inter-cell temperature variation during idle operation, and water (retained water) due to reaction product water is excessive in the end cell. It is described that an appropriate power generation of a fuel cell is realized by preventing accumulation in the fuel cell.

JP 2009-283210 A JP 2017-143020 A

However, as described in Patent Document 1, in the fuel cell, the accumulated water may accumulate in the central cell. Even if a heater is provided at the end of the fuel cell, both the end cell and the central cell are used. In some cases, the accumulated water could not be discharged appropriately in terms of time and quantity.
Accordingly, an object of the present invention is to provide a control method for a fuel cell vehicle capable of appropriately discharging the accumulated water in both the end cell and the central cell of the fuel cell during idle operation.

The control method for a fuel cell vehicle according to the present invention controls the amount of oxidizing gas theoretically derived from the target power generation amount of the fuel cell while controlling the output voltage of the fuel cell to be the target voltage during idle operation. A micro power generation step for supplying the fuel cell to the fuel cell, and after the micro power generation step, an air blow step for supplying a predetermined amount of oxidizing gas to the fuel cell for a predetermined period and discharging the accumulated water of the fuel cell. The cooling pump that adjusts the flow rate of the cooling water circulating in the fuel cell is changed to a continuous operation state, or the number of rotations of the cooling pump is increased.
Here, “during idling” means, for example, a case where the vehicle speed is 0 km / h and the torque required from the driver through the accelerator pedal is 0 N · m.

  According to the present invention, it is possible to provide a control method for a fuel cell vehicle capable of appropriately discharging the accumulated water in both the end cell and the central cell of the fuel cell during idle operation.

1 is a diagram showing a schematic configuration of a fuel cell system 1 according to Embodiment 1. FIG. It is a figure for demonstrating the control method of the fuel cell system which concerns on a comparative example. 3 is a diagram for illustrating a control method of fuel cell system 1 according to Embodiment 1. FIG. It is a figure which shows the relationship between the auxiliary machine power consumption which concerns on Embodiment 1, and increase rotation speed. 3 is a flowchart showing a processing procedure of a control method of the fuel cell system 1 according to Embodiment 1. 6 is a flowchart showing a processing procedure of a control method of the fuel cell system 1 according to Embodiment 2. 6 is a flowchart showing a processing procedure of a control method of the fuel cell system 1 according to Embodiment 3. 6 is a flowchart showing a processing procedure of a control method of the fuel cell system 1 according to Embodiment 3.

Hereinafter, the control method of the fuel cell vehicle according to each embodiment will be described with reference to the drawings.
(Embodiment 1)
The control method of the fuel cell vehicle according to the first embodiment is such that the cooling water pump that adjusts the flow rate of the cooling water circulating in the fuel cell is continuously operated at least before air blowing or after air blowing, or The auxiliary pump power consumption is increased more than usual by increasing the number of rotations of the cooling water pump.

First, the configuration of a fuel cell system that is an object of the control method for a fuel cell vehicle according to the first embodiment will be briefly described.
FIG. 1 is a diagram showing a schematic configuration of a fuel cell system 1 according to the first embodiment.
The fuel cell system 1 functions as an in-vehicle power supply system for a fuel cell vehicle. The fuel cell 10, the oxidizing gas supply system 20, the fuel gas supply system 30, the power system 40, the cooling system 50, the controller 60, the voltage sensor 71, It is composed of a current sensor 72 and the like.

The fuel cell 10 has a stack structure (not shown) in which a plurality of cells are stacked in series. The fuel cell 10 generates power by receiving supply of reaction gas (fuel gas and oxidizing gas).
The oxidizing gas supply system 20 includes a filter 21, an air compressor (ACP: Air ComPressor) 22, a bypass passage 23, shut-off valves A 1 and A 2, a bypass valve A 3 and the like, and supplies the oxidizing gas to the fuel cell 10. The air compressor 22 takes in the oxidizing gas from the atmosphere via the filter 21 and supplies it to the fuel cell 10. The bypass valve A3 adjusts the flow rate of the oxidizing gas in the bypass flow path 23.

  The fuel gas supply system 30 includes a high pressure hydrogen tank, a fuel gas supply source 31 such as a hydrogen storage alloy, a fuel gas flow path 32, a circulation flow path 33, a circulation pump (HP) 34, and the like. Hydrogen gas is supplied to the fuel cell 10. The circulation pump 34 pumps the fuel off gas discharged from the fuel cell 10 from the circulation channel 33 to the fuel gas channel 32.

The power system 40 includes a battery 41, a traction motor 42, auxiliary machinery 43, and the like, and controls charging and discharging of power. The auxiliary machinery 43 includes various heaters such as an air conditioner heater and a hot water heater.
The battery 41 is, for example, a secondary battery, and functions as a surplus power storage source, a regenerative energy storage source during regenerative braking, an energy buffer during load fluctuations associated with acceleration or deceleration of the fuel cell vehicle.

The cooling system 50 includes a radiator 51, a cooling water pump (WP: Water Pump) 52, and the like, and controls the temperature of each cell in the fuel cell 10 by circulating antifreeze cooling water or the like through the fuel cell 10.
The controller 60 controls the entire fuel cell system 1.
The voltage sensor 71 and the current sensor 72 detect the output voltage or output current of the fuel cell 10. Instead of the voltage sensor 71 and the current sensor 72, a fuel cell output sensor may be used.

  The configuration shown in FIG. 1 is obtained by adding a cooling system 50 to the configuration shown in FIG. 1 of Patent Literature 2. For details of each configuration, Patent Literatures 1 and 2 can be referred to. . That is, a known fuel cell system can be used for the fuel cell system 1.

Next, the control method for the fuel cell vehicle according to the first embodiment will be described, in particular, the control method for the fuel cell system 1 during idle operation.
First, in order to assist in understanding the control method of the fuel cell system 1 according to Embodiment 1, the control method of the fuel cell system according to the comparative example will be described.

FIG. 2 is a diagram for explaining a control method of the fuel cell system according to the comparative example.
When the controller 60 detects the idle operation state from the output values of the voltage sensor 71 and the current sensor 72, the fuel cell system 1 shifts from the normal operation mode to the intermittent operation mode, and performs normal intermittent and 0V intermittent (time t51 to time 51). t52).

  The normal operation mode is an operation mode that is selected when the load request for the fuel cell system 1 exceeds a preset reference value, and at least part of the load request including the required power of the traction motor 42 This is an operation mode provided by the power generated by the battery 10.

The intermittent operation mode is an operation mode that is selected when the load request for the fuel cell system 1 is equal to or less than a preset reference value.
The controller 60 shifts from the normal operation mode to the intermittent operation mode when it is determined that the power (output request) to be drawn from the fuel cell 10 is small and that the output power from only the battery 41 can satisfy the output request. Then, the power generation of the fuel cell 10 is temporarily stopped.

In addition, the intermittent operation mode further includes a non-power generation mode such as normal intermittent in which the fuel cell 10 stops power generation and 0 V intermittent and a micro power generation mode in which the fuel cell 10 performs micro power generation. In the 0V intermittent, the cell voltage is set to the allowable lower limit value.
In the non-power generation mode, power is supplied from the battery 41 to the auxiliary machines such as the air compressor 22 and various valves, and the battery power is greatly consumed.

When the remaining capacity SOC (State Of Charge) of the battery 41 gradually decreases to the allowable lower limit value due to normal intermittent and 0V intermittent (time t51 to t52), the normal operation mode is once returned and P charge is performed (time t52 to t52). t53).
The P charge is to increase the SOC by increasing the power generation amount of the fuel cell.

  When the SOC increases to a predetermined value due to the P charge, the operation mode is changed to the intermittent operation mode again, and normal intermittent operation (time t53 to t54) and minute power generation (time t54 to t55) are performed. Micro power generation supplies the fuel cell 10 with a necessary oxygen amount theoretically derived from a predetermined target power generation amount of the fuel cell 10 while controlling the output voltage of the fuel cell 10 to be a target voltage value. Power is supplied to the auxiliary equipment.

In normal intermittent operation, the SOC gradually decreases, and in micro power generation, the SOC is almost constant.
In the case of P charge, the cooling water pump 52 is continuously operated and the cooling water continues to circulate. In normal intermittent and micro power generation, the cooling water pump 52 is intermittently operated and the cooling water is also circulated intermittently. .

  Moreover, during P charge and micro power generation, in each cell, stagnant water derived from reaction product water increases little by little. When the accumulated water increases, stack deterioration such as mechanical deterioration of the electrolyte membrane of the fuel cell 10 and elution of the electrode catalyst occurs. This is a problem particularly in commercial fuel cell vehicles (for example, buses, taxis, forklifts, etc.) in which the shift position is put in the P range or N range and left in idle operation for a long time.

  For this reason, when the accumulated water increases to the allowable upper limit amount, it returns to the normal operation mode again, and the fuel cell has a predetermined amount, for example, obviously larger than that at the time of micro power generation, and an amount equal to or more than that at the time of P charge. Air blow for supplying the oxidizing gas for a predetermined period is performed to blow off the accumulated water (time t55 to t56). The predetermined amount of oxidant gas is an amount sufficient to blow off the stagnant water, and is an amount that does not cause the electrolyte membrane to be overdried, and is an amount that is obtained in advance by experiments and calculations. Further, the amount of hydrogen supplied during the predetermined period (hydrogen pressure) is equal to or less than that before the predetermined period.

Further, when the electrode of the fuel cell 10 becomes a high potential due to air blow during idle operation, the catalyst is eluted. Therefore, when the air blows, the current is swept from the fuel cell 10 so that the electrode does not become a high potential. 41 is charged.
After the air blow, normal intermittent (time t56 to t57) and minute power generation (time t57 to t58) are performed again, and when the accumulated water increases, air blow is performed again (time t58 to t59). That is, normal intermittent, minute power generation, and air blow are repeated in this order.

  However, during repeated normal intermittent, micro power generation, and air blow, the SOC also increases and decreases in a similar value, and in some cases, gradually increases to reach the allowable upper limit value, and the battery 41 cannot be charged beyond this value. However, it may be impossible to avoid a high potential of the fuel cell, and a new problem may occur that the fuel cell deteriorates.

  Therefore, in the control method of the fuel cell system 1 according to the first embodiment, the cooling water pump 52 is continuously operated or the cooling water pump is operated in at least one of normal intermittent and micro power generation before or after air blowing. The number of rotations of 52 is increased so that the accumulated water is properly discharged and the electrode is prevented from becoming a high potential.

FIG. 3 is a diagram for explaining a control method of the fuel cell system 1 according to the first embodiment.
The processing is the same as that in the comparative example until the controller 60 detects the idle operation state and performs normal intermittent, 0V intermittent (time t1 to t2), and P charge (time t2 to t3), and the description is omitted here. To do.

  In the first embodiment, after P charge, that is, before air blow, normal intermittent (time t3 to t4) and micro power generation (time t4 to t5) are performed, but after the start of micro power generation (time t4 to) The cooling water pump 52 is continuously operated. Thereby, the auxiliary machine power consumption is made larger than that during normal operation, for example, before the minute power generation, the SOC is further lowered, and preparation (remaining power) for charging the battery 41 by the next air blow (time t5 to t6) is made. It can be so.

  In addition, the cooling water pump 52 is continuously operated during the subsequent repetition of air blow (time t5 to t6), normal intermittent (time t6 to t7), minute power generation (time t7 to t8), and air blow (time t8 to t9). Increase power consumption of auxiliary equipment by operating. That is, after the minute power generation (from time t4), before the air blow, during the air blow, and after the air blow, while the idle operation continues, the cooling water pump 52 is continuously operated.

  In addition, the operating method of the cooling water pump 52 after micro power generation is as follows, for example. That is, in the normal operation according to the comparative example, when the cooling water pump 52 is intermittently operated, in the first embodiment, the cooling water pump 52 is continuously operated. Further, in the normal operation according to the comparative example, when the cooling water pump 52 is continuously operated, in the first embodiment, the cooling water pump 52 is continuously operated, and further, the rotation speed is set. For example, the normal operation is increased more than the P charge. Of course, in the normal operation according to the comparative example, when the cooling water pump 52 is intermittently operated, in the first embodiment, the cooling water pump 52 is operated intermittently, and the rotation speed is set. You may make it increase.

FIG. 4 is a diagram showing the relationship between the auxiliary machine power consumption and the increased rotational speed according to the first embodiment.
Thus, the increased number of revolutions of the cooling water pump 52 can be changed according to the auxiliary machine power consumption (or SOC reduction speed, SOC), the amount of power generated by air blow, and the like.

  In addition, by operating the cooling water pump 52 continuously or increasing the number of rotations of the cooling water pump 52, the internal temperature of the stack becomes uniform during micro power generation, and the power generation state of the fuel cell 10 is also uniform. As a result, the accumulated water in the stack becomes uniform. As a result, the drainage capability of the air blow can be further improved.

FIG. 5 is a flowchart showing a processing procedure of the control method of the fuel cell system 1 according to the first embodiment.
The controller 60 determines whether the shift position is in the P range (idle operation) during the normal operation mode (step S10) (step S20).
If it is determined that it is in the P range (YES in step S20), it is determined whether minute power generation is being performed (minute power generation flag ON) (step S30).

If it determines with performing micro power generation (YES of step S30), the cooling water pump 52 will always be driven or the rotation speed of the cooling water pump 52 will be increased, and the power consumption of the cooling water pump 52 will be increased. (Step S40). As a result, the SOC gradually decreases.
Then, after increasing the power consumption of the cooling water pump 52, for example, the process returns to step S20 (step S50).

  In addition, when it determines with not being in the P range (NO of step S20), when it determines with not performing micro power generation (NO of step S30), it returns to step S20, for example (step S50).

  As described above, the control method for the fuel cell vehicle according to the first embodiment operates the cooling water pump 52 continuously at least before air blowing or after air blowing, Increase the number of revolutions, increase the auxiliary machine power consumption more than usual, properly discharge the accumulated water of each cell, avoid the electrode to become high potential, and further suppress the excessive increase of SOC Is something that can be done.

(Embodiment 2)
The control method for the fuel cell vehicle according to the second embodiment is such that the circulation pump that pumps the fuel off-gas discharged from the fuel cell from the circulation channel to the fuel gas channel continuously at least before air blowing or after air blowing. The power consumption of the auxiliary machine is increased more than usual by increasing the rotational speed of the circulation pump.

  The configuration of the fuel cell system that is the target of the control method for the fuel cell vehicle according to the second embodiment may be the same as that of the fuel cell system 1 according to the first embodiment, and the description thereof is omitted here.

FIG. 6 is a flowchart showing a processing procedure of the control method of the fuel cell system 1 according to the second embodiment.
In the first embodiment, the cooling water pump 52 is continuously operated or the number of rotations of the cooling water pump 52 is increased after the minute power generation shown in FIG. 3 (from time t4). 2, after the minute power generation (from time t <b> 4), instead of the cooling water pump 52, the circulation pump 34 is continuously operated, or the rotation speed of the circulation pump 34 is increased.

  The processing procedure (steps S110 to S130) until it is determined whether or not minute power generation is performed is the same as that of the first embodiment shown in FIG. 5 (steps S10 to S30), and description thereof is omitted here.

If it is determined that micro power generation is being performed (YES in step S130), the circulation pump 34 is always driven, or the number of rotations of the circulation pump 34 is increased from that in the normal operation, for example, compared with the P charge. Then, the power consumption of the circulation pump 34 is increased (step S140). As a result, the SOC gradually decreases.
Then, after increasing the power consumption of the circulation pump 34, for example, the process returns to step S120 (step S150).

  By continuously operating the circulation pump 34 or increasing the number of rotations of the circulation pump 34, the water content in the cell surface becomes uniform and the power generation state of the fuel cell 10 becomes uniform. The accumulated water becomes uniform. Thereby, the drainage capacity of the air blow can also be improved.

  As described above, the control method of the fuel cell vehicle according to the second embodiment operates the circulation pump 34 continuously at least before air blow or after air blow, or the rotation speed of the circulation pump 34. , The accumulated water in each cell can be appropriately discharged, the electrode can be prevented from being at a high potential, and the excessive increase in SOC can be suppressed.

(Embodiment 3)
The control method for a fuel cell vehicle according to the third embodiment increases the rotational speed of an air compressor that takes in oxidizing gas from the atmosphere via a filter and supplies it to the fuel cell at least before air blow or after air blow. As a result, the power consumption of auxiliary equipment is increased more than usual.

  The configuration of the fuel cell system that is the target of the control method for the fuel cell vehicle according to the third embodiment may be the same as that of the fuel cell system 1 according to the first embodiment, and the description thereof is omitted here.

FIG. 7 is a flowchart showing the processing procedure of the control method of the fuel cell system 1 according to the third embodiment.
In the first and second embodiments, the cooling water pump 52 or the circulation pump 34 is continuously operated after the minute power generation shown in FIG. 3 (from time t4), or the rotation speed of the cooling water pump 52 or the circulation pump 34 is reached. However, in the third embodiment, after the minute power generation (from time t4), the rotation speed of the air compressor 22 is increased instead of the cooling water pump 52 or the circulation pump 34.

The processing procedure (steps S210 to S230) until it is determined whether or not minute power generation is performed is the same as that in the first embodiment shown in FIG. 5 (steps S10 to S30), and the description thereof is omitted here.
If it determines with performing micro electric power generation (YES of step S230), the opening degree of bypass valve A3 will be increased (step S240). Thereby, even if the flow rate of the oxidizing gas supplied from the air compressor 22 increases next, the flow rate of the oxidizing gas supplied to the fuel cell 10 does not increase, and the power generation amount of the fuel cell 10 does not increase. The SOC does not increase.

Then, the rotational speed of the air compressor 22 is increased from that before the minute power generation, and the power consumption of the air compressor 22 is increased (step S250). As a result, the SOC gradually decreases.
After increasing the power consumption of the air compressor 22, for example, the process returns to step S220 (step S260).

  As described above, the control method for the fuel cell vehicle according to the third embodiment increases the rotational speed of the air compressor 22 at least before air blow or after air blow so that the retained water in each cell is appropriately adjusted. It is possible to discharge and avoid the electrode from becoming a high potential, and furthermore, it is possible to suppress an excessive increase in SOC.

(Embodiment 4)
In the control method for a fuel cell vehicle according to the fourth embodiment, the power supplied to the various heaters is increased at least one before or after the air blow to increase the power consumption of the auxiliary equipment more than usual.

  The configuration of the fuel cell system that is the target of the control method for the fuel cell vehicle according to the fourth embodiment may be the same as that of the fuel cell system 1 according to the first embodiment, and the description thereof is omitted here.

FIG. 8 is a flowchart showing the processing procedure of the control method of the fuel cell system 1 according to the fourth embodiment.
In the first to third embodiments, the cooling water pump 52 or the circulation pump 34 is continuously operated after the minute power generation shown in FIG. 3 (from time t4), or the cooling water pump 52, the circulation pump 34 or the air compressor is operated. In the fourth embodiment, the power supplied to various heaters such as an air conditioner heater and a hot water heater is increased after the minute power generation (from time t4).

  The processing procedure (steps S310 to S330) until it is determined whether or not the minute power generation is performed is the same as that of the first embodiment shown in FIG. 5 (steps S10 to S30), and the description is omitted here.

If it determines with performing micro power generation (YES of step S330), micro power generation will be performed and the electric power supplied to various heaters will be increased rather than before micro power generation (step S240). As a result, the SOC gradually decreases.
And after increasing the electric power supplied to various heaters, for example, it returns to Step S320 (Step S260).

  In the fourth embodiment, since a heater heat source is obtained, it can be used for warming up auxiliary components when it is desired to use the heat source, for example, when idling in a cold region below freezing. The amount of increase in the power supplied to the various heaters may be a fixed value, or may be set based on the amount of power generated by air blow. You may set from the required calorific value.

  As described above, the control method for the fuel cell vehicle according to the fourth embodiment increases the power supplied to the various heaters at least before air blow or after air blow so that the retained water in each cell is appropriately It is possible to discharge and avoid the electrode from becoming a high potential, and furthermore, it is possible to suppress an excessive increase in SOC.

Embodiments 1 to 4 can be combined as a control method for a fuel cell system according to another embodiment. In addition, the auxiliary machine for increasing the auxiliary machine power consumption is not limited to the cooling water pump 52, the circulation pump 34, the air compressor 22, and various heaters.
In each embodiment, the shift position is in the “P range”, but the shift position may be in the “N range”.

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Fuel cell 20 Oxidizing gas supply system 22 Air compressor 30 Fuel gas supply system 34 Circulation pump 40 Electric power system 41 Battery 43 Auxiliary machinery 50 Cooling system 52 Cooling water pump 60 Controller 71 Voltage sensor 72 Current sensor A1, A2 Air valve A3 Bypass valve

Claims (1)

During idle operation,
A micro power generation step for supplying the fuel cell with an amount of oxidizing gas theoretically derived from the target power generation amount of the fuel cell while controlling the output voltage of the fuel cell to be a target voltage;
An air blow step for supplying a predetermined amount of oxidizing gas to the fuel cell for a predetermined period after the micro power generation step and discharging the accumulated water of the fuel cell;
In the micro power generation step, the cooling pump for adjusting the flow rate of the cooling water circulating in the fuel cell is changed to a continuous operation state, or the number of revolutions of the cooling pump is increased.

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